Proactive Threat Hunting: Taking the Fight to the Enemy

If you haven't implemented a cyber threat hunting capability yet, 2018 is the time to start. Anyone who has paid attention to recent data breaches will know that attackers have become dangerously good at breaking into and hiding on enterprise networks for long periods of time. Often organizations do not realize they have been breached for months, and in some cases years, after an initial intrusion and even then only when informed of it by a third-party.

Security strategies solely focused on blocking attacks at the perimeter and responding to incidents after they have occurred are no longer enough for dealing with targeted, stealthy and persistent attackers. You also need measures for proactively hunting down and neutralizing threats on your network before they materialize.

With threat hunting, your incident response team is going out and engaging with the enemy, rather than passively waiting for them to show their hand. As the SANS Institute describes it, "threat hunting is a focused and iterative approach to searching out, identifying and understanding adversaries that have entered the defender’s networks." 

It involves the use of external threat intelligence, internal telemetry and other data to uncover adversaries who have the intent, the ability, and the opportunity to do harm. If implemented correctly, a threat hunting capability can reduce attacker dwell time on your network, and also your exposure to new risks.

Threat hunting requires a very different mindset from one that is focused primarily on reacting to security incidents and alerts. It's main objective is finding the hidden human adversary on your network rather than just their tools and malware. It requires you to think like the adversary and to know what systems and data on your network an attacker will most likely target so you can start protecting those assets first.

A good incident response team is vital to threat hunting;unless you can quickly mitigate and recover from the threats you find, there's not a whole lot that can be gained from going out and finding them in the first place. This is particularly true as your threat hunting team's capabilities mature. Just as the hunters get quicker and better at finding new threats, your IR team needs to be able to prioritize and respond to the identified threats equally effectively.

To be effective at hunting, security teams also need access to a lot of internal and external telemetry and threat intelligence. For example, to find a hidden adversary, you need to know what to look for, where and when. Often, that task requires correlating data from multiple sources, which in turn requires a high degree of automation. You need tools for automatically collecting and aggregating data from multiple sources and for quickly cross-referencing and analyzing the data.

Having trained analysts with a diverse range of skills on your team is another necessity. Those include  security operations skills, incident response, forensics, and malware analysis.

Clearly, pulling together everything you need to be effective at threat hunting is not easy but it's definitely worthwhile.  Many forward-looking organizations have already adopted threat-hunting practices and more are following suit daily. In an April 2017 SANS Institute survey, 27% of the 306 enterprises that participated had a defined threat-hunting program in place and were following it. Another 45% engaged in threat hunting even if it was only on an ad hoc basis and without any formal processes. Organizations that achieved measurable improvements in security as the result of threat hunting, most often cited speed and accuracy as their biggest gain.

Hunting is about taking a proactive approach to dealing with threats on your network. Make adoption of at least some of its approaches a priority this year.

To learn more about linking security intelligence to policy enforcement to defend against advanced threats click here.